Method and device for controlling a targeted thermal deposition into a material

ABSTRACT

Disclosed is a process for controlling selective application of heat into a material, preferably into a biological material, having an ultrasonic-wave generating unit which couples the ultrasonic waves into the material, an ultrasonic-wave-detecting unit which detects the ultrasonic waves emerging from the material and an evaluation unit which generates information-providing parameters on the basis of the detected ultrasonic waves which provide information about the thermal and structural changes inside the material.

TECHNICAL FIELD

The present invention relates to a process and device for controllingselective application of heat into a material, preferably intobiological tissue, having an ultrasonic-wave-generating unit whichcouples ultrasonic waves into the material, an ultrasonic-wave-detectingunit which detects the ultrasonic waves emerging from the material andan evaluation unit which generates information-providing parametersrelating to the thermal and structural changes inside the material onthe basis of the detected ultrasonic waves.

STATE OF THE ART

Processes of the aforementioned class can be used in material researchand material processing in general, in particular with materialstructures which thermal influence may alter structurally. Of particularinterest here are also thermotherapy processes, which are employed inselective hyperthermy of confined areas of tissue, in particular intreating tumors and metastases.

Such types of thermotherapy processes applied today can be divided intotwo groups:

1. Moderate heating to 43° C. from the outside by means of fields:

So-called hyperthermy refers to heating regions of tissue inside thebody by means of external energy input. It is used in oncology fortreating tumors, e.g. to supplement radiation or chemotherapy. Energyinput occurs by means of electrical alternating fields or by means ofhigh energy ultrasound. The therapeutically desired increases intemperature are usually about 6° C. above the internal body temperature,which is usually obtained with treatment periods from 20 to 30 minutes.

2. Generating thermal necrosis at temperatures from 45° C. to 200° C. byintracavitary or minimal-invasive processes:

Confined local thermal tissue damage is a widespread procedure inminimal-invasive surgery and endosurgery in treating pathologicalchanges in tissue, such as tumors and metastases. The most commonintracavitary or minimal-invasive methods consist of usinginfrared-range laser light (LITT: laser-induced thermotherapy),high-frequency coagulator and high-energy ultrasound (HIFU:

high-intensity focused ultrasound). In these applications, essentiallythe following tissue reactions occur: solely heating, tissue expansion,denaturation (coagulation), gas bubble formation. Subsequentcarbonization is therapeutically undesirable. Examples of the diverseapplications are treating liver metastases, mammary carcinoma, prostatetumors and brain tumors. Sometimes, for instance in the treatment ofliver metastases, structural damage is achieved by using cold(cryotherapy) or alcohol. In the treatment of the prostrate, hot watermay also be applied to the target region instead of laser light orultrasound.

In endosurgery in the gastrointestinal tract, laser applicators or HFapplicators are utilized, e.g. for esophageal varices or for wideningstenoses.

The overall therapeutic goal of these methods of therapy is maximumdamage to the malignant tissue while preserving the surrounding benigntissue regions, which may consist of extremely sensitive structuresdepending on the nature of their function.

A special case is using infrared laser light for treating glaucoma.Glaucoma is the main cause of blindness in the western countries. Theend of a laser fiber is placed from the exterior onto the sclera and thechamber-water producing structures below are coagulated (transscleralcyklophoto coagulation). Too high laser temperatures result inundesirable total damage (disruption) of the irradiated ciliar part ofthe body. With treatment times of two seconds, switching-off criteriafor the laser would be of help provided coagulation is good.

Efficiency and further gaining ground of these methods of treatment aretherefore closely tied to the availability of a non-invasive procedure,which informs the surgeon in real time about the current therapeuticeffect, respectively provides the control parameter or control signalsfor back coupling to the heat-generating system.

As these effects generally are dependent on the temporal temperaturegradients, solely indicating the attained tissue temperature isinsufficient for monitoring the therapy. Particularly in view of theindividual, tissue-specific and tumor-specific differences, evidence ofstructural tissue changes is more precise and informative regarding thecurrent, achieved therapeutical effect than the attained tissuetemperature.

Hitherto, there are no inexpensive methods of non-invasive or minimalinvasive realtime control for these therapy procedures.

Previous approaches at utilizing diagnostic ultrasound for therapycontrol have aimed solely at giving the attained tissue temperatures.The pertinent literature proposes, i.e., processes to achievethermometry by measuring the temperature-dependent velocity of soundpropagation. See:

Seip. E. S. Ebbini, “Noninvasive Estimation of Tissue TemperatureResponse to Heating Fields Using Diagnostic Ultrasound,” IEEE Trans.Biomed. Eng., vol. 42; August 1995.

Seip, P. VanBaren, C. Simon, E. S. Ebbini, “Non-Invasive Saptio-TemporalTemperature Estimation Using Diagnostic Ultrasound,” IEEE UltrasonicsSymposium Proceeding, 1995.

Seip, P. VanBaren, C. A. Cain, E. S. Ebbini, “Noninvasive Real-TimeMultipoint Temperature Control for Ultrasound Phased Array Treatments”,IEEE Trans. Ultrason., Ferroelect., Freq. Contr., vol. 43, November1996.

C. Simon, P. VanBaren, E. S. Ebbini, “Quantitative Analysis andApplications of Noninvasive Temperature Estimation Using DiagnosticUltrasound” IEEE Ultrasonics Symposium Proceeding, October 1997.

C. Simon,. P. VanBaren, E. S. Ebbini, “Two-Dimensional TemperatureEstimation Using Diagnostic Ultrasound,” IEEE Trans. Ultrason.,Ferroelect., Freq.Contr., vol 45, July 1998.

DE 195 06 363 A1 describes a process for non-invasive thermometry inorgans under hyperthermic and coagulation conditions. In order to obtaindata about structural changes, in this process the to-be-heated tissueis bombarded with ultrasonic waves. The amplitude reflection factor ofthe tissue is measured in the form of a signal. Then, on the basis ofthe obtained amplitude reflection factors, the sum is determined fromthe temperature-dependent and structure-dependent changes in the tissueexposed to the heat.

When applied to thermal material treatment for selective internalstructural changes in materials, in general, for example the transitionfrom crystalline to amorphous or a chemical change, there are also noknown reliable processes for when and in which regions structuralchanges occur. The preceding known processes for determining thetemperature in the path of the applied thermotherapy and hyperthermy arenot suited for precise determination of the structural change and thecurrent spatial extent and of the structural change occurring inside amaterial.

DESCRIPTION OF THE INVENTION

The present invention improves a process and is a device for controllingselective application of heat into a material, preferably biologicaltissue, having an ultrasonic-wave-generating unit which couples theultrasonic waves into the material, an ultrasonic-wave-detecting unitwhich detects the ultrasonic waves emerging from the material and anevaluation unit which generates information providing parameters for thethermal and structural changes inside the material based on the detectedultrasonic waves, in such a manner that an unequivocal statement can bemade about the type and extent of structural change inside the materialdue to the heat input. Furthermore, the present invention makes possiblecontrolling the heat input into the material in such a manner that thedesired goal of the treatment inside the material can be achievedwithout causing undesired structural changes. Finally the invention is adevice for performing this process.

An element of the present invention is a process in which the ultrasonicwaves emerging from the material are detected time-resolved andsite-resolved, with the detected ultrasonic waves being time-resolved inthe evaluation unit and being examined for their change of propagationtime relative to the ultrasonic-wave signals stemming from the detectedultrasonic waves which are reflected at the material prior toapplication of heat and are used as the basis for spatial limitation ofthe structural changes occurring in the path of the heat input. Based onthe objective of the treatment in the material and the determinedstructural changes in the material, the energy input into the materialper time required for the application of heat is controlled.

Contrary to the previous methods in which solely one ultrasonicparameter is proposed for monitoring the temperature, in the process ofthe invention values are provided with which the structural tissuechanges can be measured directly and their temporal formation behaviorcan be spatially detected.

Therefore, the present invention is based upon utilizing thesite-resolved change in the delay time of the backscattered ultrasonicwaves to directly determine the structural material change caused in thepath of the application of heat. Thus, for example, structuralbiological tissue irritation can be detected not indirectly, ashitherto, by determining the temperature but by utilizing solely thechange in the delay time of the backreflected ultrasonic waves.

In order to be able to detect any changes in the delay time behavior atall, a scale has to first be determined which is obtained at thematerial to be examined and material to be treated with the applicationof heat. Therefore, the detected backscattered ultrasonic waves atrespectively and the material and their ultrasonic-wave signals arestored accordingly before heat is selectively applied to the material.The measured signals are spectrally detected by means of the detectingunit.

Subsequently, the to-be-treated material is selectively heated, forexample by means of introducing laser light locally with the aid of afiber optical waveguide. However, other methods of selective applicationof heat are also possible, such as for example exposing the material toexternal electromagnetic alternating fields or ultrasonic fields, withlow-frequency ultrasound being employed for heating and high-frequencydiagnostic ultrasound for detection. Another method is deep-freezingusing liquid nitrogen.

The application of heat is controllable according to the degree ofenergy introduced into the material per time unit. Thus, if light isapplied, the luminous power can be set accordingly.

For detection and monitoring of the heat input into the material, thebackreflected ultrasonic waves are detected during heat input in such amanner that they are detected temporally and simultaneously completelyspectrally. The obtained ultrasonic-waves signals are processedtime-resolved per transmitted ultrasonic pulse, with in the examinationof backreflection ultrasonic-wave signal regions being sought, in whicha maximum change in the delay time compared to the scale is observed. Onthe basis of the measuring geometry, exact information about thelocation and the expansion of the structural changes inside the materialcan be derived from the profile of the echo signal. Using thisinformation about the current state inside the material, controlledvariables for actuating the heat applying unit can be generated in orderto obtain only desired structural material changes. In particular, intreating biological tissue, only those regions of tissue should havesufficient heat applied that are to be selectively destroyed but therespective adjacent tissue regions should be protected from too highheat input.

Furthermore, in combination with the aforedescribed examination usingintegrated backscattering of the ultrasonic-wave signals received perultrasonic impulse, a criterion can be obtained in order to be able todetect structural changes in process, for example ranging from theorigin and spatial formation of gas bubbles in biological tissue tocharring.

Qualitative and quantitative evaluation of the structural changeoccurring in the material due to heat input can therefore be made bysite-resolved measuring of the changes in the delay time of theultrasonic waves. The changes in the delay time comprise thetemperature-dependent velocity of propagation of sound c(T) and withfurther heating of the naturally diverse thermally induced expansion ofthe material ε(T). The variable c(T) is used for pure thermometry, forinstance for moderate heating and low temperature increases.

Determination of the spatial gradient of the delay time changes alongthe treated material volume yields the maximum spatial shifts ofbackscattered ultrasonic signal portions, which are directly connectedwith the structural change of the material and serve to indicate theirspatial expansion.

However, both effects can be separated, on the one hand, on the basis ofdistinctly strong influences of the macroscopic material expansionreflected in a strong temporal gradient of the delay time changes; onthe other hand, in the direction and diverse propagation of the effectaway from the origin. Changes in the so-called “integratedbackscattering” relative to an output value before heat input orrelative to a characterizing, structural material change during heatinput are used to control gas formation in the biological tissue to betreated with heat. Subsiding of this effect indicates imminentcarbonization of the tissue.

As an alternative to the aforedescribed manner of examining the changesin the delay time of the backreflected ultrasonic waves and theirevaluation, changing the acoustic damping coefficient can be used as aninformation-providing parameter for determining the structural change ina material, preferably into a biological material.

An alternative element of the process of the invention is, therefore, todevelop a generic process in such a manner that the ultrasonic wavesemerging from the material are detected time-resolved and site-resolved,with the detected ultrasonic waves per ultrasonic pulse being windowedin temporally dynamically adapted time windows in the evaluation unit insuch a manner that the beginning part of each time window section has afixed relationship to the signal course of the detected ultrasonicwaves. For each current time window section, a direct or indirectspectral comparison is conducted with at least one time window sectionof a temporally older ultrasonic-wave pulse which with reference to thetemporal signal course has the same beginning part of the section as thecurrent time window section. The terms “direct” and “indirect” indicatethe ability to analyze the spectral signal course in the temporal rangeas well as in the frequency range, ensuring that only those time windowsections are compared that also belong to one and the same reflectionregion inside the to-be-treated material. Using this spectralcomparison, an estimation is made of the temporal behavior of thedamping coefficient of the material at which the ultrasonic wavescorresponding to the detected signals in the individual time windowsections are reflected. The temporal behavior of the damping coefficientinside the respective material region to be derived therefrom serves asthe basis for a spatial limitation of structural changes occurringinside the material in the path of the heat input. Finally, based on theobjective of the treatment in the material and the determined structuralchanges in the material, heat input per time into the material requiredfor heat application into the material is controlled.

Comparison of a local damping coefficient at various points in timebefore respectively during heat input for determining a change in thematerial is only useful if the region for which the damping coefficientis estimated is always the same, i.e. it only need be ensured that inthe examination of individual regions of tissue, all the reflectedultrasonic signals that belong to temporally different ultrasonic pulsesare compared which also are reflected from the same region of thematerial.

This is achieved by the reflected signal for determining the localspectra not being provided with a temporally rigid time window, butrather with a dynamic, accompanying time window. Accompanying in thesense that the reflected signal is subdivided into individual sectionsof the same size, with the beginnings of the sections of each timewindow always being in a fixed relationship regarding the entire courseof the backreflected signal. This accompanying time window can, forexample, be determined by the known correlation processes.

Comparison of the spectral information of a signal in an accompanyingtime window for estimation of the damping coefficient ensures in thismanner that the site of the region for which the damping coefficient isestimated is fixed with regard to the material.

Therefore, detection of a change in the damping coefficient is used todetermine site-resolved the structural change in the material.

Spectral shifting is used to determine the damping coefficient betweentwo respective time window sections. Due to the frequency dependency ofthe damping coefficient while passing a damping layer, an ultrasonicsignal is weakened in a varying manner in its spectral parts, therebyresulting in shifting the entire spectrum of the signal in the frequencyrange. This shifting of the spectrum can be determined by various knownmethods. Determination of the shift can be carried out in the temporalrange as well as in the frequency range.

In order to estimate the site-resolved damping coefficient using thespectral shifting method, the reflected ultrasonic signal is dividedinto individual time window sections, thus temporally time windowed, andthe relative shift of the spectra of these time windows relative to eachother is observed. From a shift of the spectra relative to each other,the average damping coefficient can be estimated for the region betweenthe respective time windows.

The method of spectral difference is analog except that the dampingcoefficient is not determined by shifting the spectra but by thevariance of the spectra.

To conduct the process of the invention, a device for controlling theselective application of heat into a material, preferably for gentletreatment of biological materials, in particular biological tissue,having an ultrasonic wave generating unit which couples the ultrasonicwaves into the material, an ultrasonic wave detecting unit which detectsthe ultrasonic waves emerging from the material, and an evaluation unitwhich generates on the basis of the detected ultrasonic wavesinformation-providing parameters which provide information about thethermal and structural changes inside the material, is further improvedin such a manner that the ultrasonic-wave-generating unit and theultrasonic-wave-detecting unit are disposed in the same plane and arejointly adjustable relative to the to-be-treated material, and that aheat-application effecting unit is disposed mainly in the center of theultrasonic-wave-generating and the ultrasonic-wave-detecting unit and isdirected at the material.

Further features can be found in the following description withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is made more apparent in the following without theintention of limiting the scope or spirit of the inventive idea usingpreferred embodiments with reference to the accompanying drawings,showing in:

FIGS. 1a and b are a diagram of the delay time shift of a reflectedultrasonic-wave pulse and a photograph of tissue damage due to localheat input,

FIG. 2 is a first device for carrying out the process,

FIG. 3 is a second device for carrying out the process and

FIG. 4 is a third device for carrying out the process.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a diagram in which the depth of penetration of anultrasonic-wave pulse into a material is plotted along the abscissa, inthe example of FIGS. 1a and b in biological tissue. The values for thesite-resolved delay time shifts for an ultrasonic-wave pulse in μsec isplotted along the ordinates.

FIG. 1a shows the delay time shift representable per ultrasonic-wavepulse, which is coupled into the biological tissue, relative to thebeginning of the course of an ultrasonic pulse detected at normaltemperature conditions, i.e. without artificial heat input.

The change in the delay time of an ultrasonic pulse due to of astructural change inside the tissue region as a result of the influenceof heat is obtained with the aid of cross correlation of the currentlyobtained ultrasonic wave signals with the values stored prior tocommencing treatment. Thereupon, the obtained curve is evaluated using apolynomial preferably of a lower order, smoothened and evaluatedaccordingly.

As FIG. 1a shows, in particular, those regions of the curve in which thegradient of the change in the delay time is the greatest is taken intoaccount. This is illustrated by the two vertical boundary lines whichsimultaneously limit a spatial region of structural changes that werealready determined inside the tissue. In FIG. 1b, which is a photographof the pertinent, heat-treated region of tissue, the light region oftissue corresponds precisely with the region in which structural tissueirritations due to heat input were observed. This region correspondsexactly to the region in which the function in FIG. 1a has the largestgradient. The heat input in FIG. 1b occurs by means of applying lightusing a fiber optical waveguide which projects from the below into thetissue region in the center of the photograph of FIG. 1b.

In order to draw conclusions about the temperature from the values ofthe delay time shift, it is necessary to calculate the site-resolvedpropagation velocities which again form the basis for determining thetemperature which are used to control and document the preservation ofthe healthy tissue.

FIG. 2 shows a preferred embodiment for carrying out the process of theinvention.

An ultrasonic transducer 1 for ultrasound generation and simultaneouslyfor detection is located on a housing part G having a sphericallycontoured underside. Provided in the center of housing G and ultrasonictransducer 1 is a bore hole through which a fiber optical waveguide 3 isled for selective application of light to the tissue volume 4.

Conventional piercing acoustic heads can be used to ensure unequivocalaiming of the ultrasonic beam at the to-be-treated tissue volume 4.Instead of the provided guiding of the piercing needles, a fiber opticalwaveguide 3, which can also be replaced by a HF applicator, is suited inthe illustrated case.

However, special acoustic transducers are proposed to unequivocally fixthe geometric factors which influence the process and therefore mustalways be taken into account:

Single element transducers, as shown in FIG. 2, which can also be shapedfocusing having a central bore hole 2 for receiving the fiber opticwaveguide 3 or a high-frequency needle. The coaxial setup ensures theunequivocal aim of the sound beam at the to-be-treated tissue region 4.

FIG. 3 shows a preferred embodiment having an ultrasonic transducerlinear array 5 having a bore hole 2 for receiving heat applicators 3.The array permits achieving electronic depth focusing which aidspositioning the applicator, however particularly ensures measuring andrepresentation of the degree and expansion of the therapeuticallyachieved tissue change. In addition, the array can be disposed in arotatable manner about the applicator axis 6 inside a housing 7permitting three-dimensional guidance of the sound beam by means ofwhich detection and representation of the three-dimensional tissuechanges occur. In this manner, optimum compensation of three-dimensionalmovement influences is achieved.

The same can be achieved with a 2D-array 8, as shown in FIG. 4, having arespective bore hole 2 for receiving an applicator 3 and electronicsound field guidance, with the advantage of obviating manual rotationmovements. In addition, the fiber optic waveguides or HF applicators canbe provided with markers (e.g. made of metal) which are especiallyeasily recognizable for ultrasound.

All the preferred embodiments are sterilizable, respectively can beprovided with sterile coats.

List of Reference Numbers

1 ultrasound transducer

2 bore hole

3 fiber optic waveguide

4 tissue region

5 linear transducer array

6 axis of rotation

7 housing

8 single element of a two-dimensional transducer array

What is claimed is:
 1. A process for controlling selective applicationof heat into a material with an ultrasonic wave generating unit whichcouples ultrasonic waves into the material, an ultrasonic wave detectingunit which detects the ultrasonic waves emerging from the material andan evaluation unit which generates structural and thermal parameters ona basis of the detected ultrasonic waves which provide information aboutthermal and structural changes inside the material comprising: detectingultrasonic waves emerging from the material over a time period of heattreatment; examining the detected ultrasonic waves from the material todetermine a location of structural change in the material caused by theheat treatment at which a maximum delay change in the detectedultrasonic waves occurs; and controlling the application of heat to thelocation of the structural changes to accomplish a heat treatment planfor the material.
 2. The process according to claim 1 wherein:ultrasonic wave signals produced by the ultrasonic wave detecting unitreceiving ultrasonic waves reflected by the material are spectrallydetermined and integrated over a frequency range of the ultrasonicwaves; a change of an integral of the reflected ultrasonic waves overtime beginning from a starting value of the integral obtained beforeheating of the material is determined; and a parameter about gas bubbleformation inside the material based upon the change of the integral isformed.
 3. The process according to claim 2, wherein: the starting valueof the integral occurs at the beginning of application of heat at aknown temperature and serves as a reference value for detecting changesin the value of the integral.
 4. The process according to claim 2wherein: after changes in the value of the integral have decreased,obtaining a parameter about imminent carbonization inside the material.5. The process according to claim 3 wherein: after changes in the valueof the integral have decreased, obtaining a parameter about imminentcarbonization inside the material.
 6. The process according to claim 1wherein: in the evaluation unit, the detected ultrasonic waves of anultrasonic pulse are dynamically time windowed so that each individualtime window is in a fixed relationship to the detected ultrasonic waves;for each current time window, a spectral comparison is conducted with atleast one time window of an earlier ultrasonic-wave which, has a samebeginning as the current time window; from the spectral comparisonconducting a time estimation of a damping coefficient of the materialfor the ultrasonic waves corresponding to detected signals in the timewindow; utilizing the time estimation of the damping coefficient toprovide a location of structural changes occurring inside the materialin a path of the heat input; and based upon a heat treatment plan forthe material and the structural changes in the material, controlling anenergy input over time into the material which is required to accomplishthe heat treatment plan.
 7. A process for controlling selectiveapplication of heat into a material with an ultrasonic wave generatingunit which couples ultrasonic waves into the material, an ultrasonicwave detecting unit which detects the ultrasonic waves emerging from thematerial and an evaluation unit which generates structural and thermalparameters on a basis of the detected ultrasonic waves which provideinformation about thermal and structural changes inside the materialcomprising: detecting ultrasonic waves emerging from the material; timewindowing the detected ultrasonic waves of an ultrasonic pulsedynamically in the evaluation unit so that each individual time windowis in a fixed relationship to the detected ultrasonic waves; conductinga spectral comparison for each current time window with at least onetime window of an earlier ultrasonic wave, which has a same beginning asthe current time window; conducting a time estimation of a dampingcoefficient of the material for the ultrasonic waves corresponding todetected signals in the time window based on the spectral comparison;utilizing the time estimation of the damping coefficient to provide alocation of structural changes occurring inside the material in a pathof the heat input; and controlling the application of heat to thelocation of the structural changes to accomplish a heat treatment planfor the material.
 8. The process according to claim 2 wherein: in theevaluation unit, the detected ultrasonic waves of an ultrasonic pulseare dynamically time windowed so that each individual time window is ina fixed relationship to the detected ultrasonic waves; for each currenttime window, a spectral comparison is conducted with at least one timewindow of an earlier ultrasonic-wave, which has a same beginning as thecurrent time window; from the spectral comparison conducting a timeestimation of a damping coefficient of the material for the ultrasonicwaves corresponding to detected signals in the time window; utilizingthe time estimation of the damping coefficient to provide a location ofstructural changes occurring inside the material in a path of the heatinput; and based upon a heat treatment plan for the material and thestructural changes in the material, controlling an energy input overtime into the material which is required to accomplish the heattreatment plan.
 9. The process according to claim 3 wherein: in theevaluation unit, the detected ultrasonic waves of an ultrasonic pulseare dynamically time windowed so that each individual time window is ina fixed relationship to the detected ultrasonic waves; for each currenttime window, a spectral comparison is conducted with at least one timewindow of an earlier ultrasonic-wave, which has a same beginning as thecurrent time window; from the spectral comparison conducting a timeestimation of a damping coefficient of the material for the ultrasonicwaves corresponding to detected signals in the time window; utilizingthe time estimation of the damping coefficient to provide a location ofstructural changes occurring inside the material in a path of the heatinput; and based upon a heat treatment plan for the material and thestructural changes in the material, controlling an energy input overtime into the material which is required to accomplish the heattreatment plan.
 10. The process according to claim 4 wherein: in theevaluation unit, the detected ultrasonic waves of an ultrasonic pulseare dynamically time windowed so that each individual time window is ina fixed relationship to the detected ultrasonic waves; for each currenttime window, a spectral comparison is conducted with at least one timewindow of an earlier ultrasonic-wave, which has a same beginning as thecurrent time window; from the spectral comparison conducting a timeestimation of a damping coefficient of the material for the ultrasonicwaves corresponding to detected signals in the time window; utilizingthe time estimation of the damping coefficient to provide a location ofstructural changes occurring inside the material in a path of the heatinput; and based upon a heat treatment plan for the material and thestructural changes in the material, controlling an energy input overtime into the material which is required to accomplish the heattreatment plan.
 11. The process according to claim 10 wherein: in theevaluation unit, the detected ultrasonic waves of an ultrasonic pulseare dynamically time windowed so that each individual time window is ina fixed relationship to the detected ultrasonic waves; for each currenttime window, a spectral comparison is conducted with at least one timewindow of an earlier ultrasonic-wave, which has a same beginning as thecurrent time window; from the spectral comparison conducting a timeestimation of a damping coefficient of the material for the ultrasonicwaves corresponding to detected signals in the time window; utilizingthe time estimation of the damping coefficient to provide a location ofstructural changes occurring inside the material in a path of the heatinput; and based upon a heat treatment plan for the material and thestructural changes in the material, controlling an energy input overtime into the material which is required to accomplish the heattreatment plan.
 12. The process according to claim 6, wherein: thespectral comparison is conducted in one of a time period or a frequencyrange in response to spectral variance or spectral shift of the detectedultrasonic waves.
 13. The process according to claim 7, wherein: thespectral comparison is conducted in one of a time period or a frequencyrange in response to spectral variance or spectral shift of the detectedultrasonic waves.
 14. The process according to claim 8, wherein: thespectral comparison is conducted in one of a time period or a frequencyrange in response to spectral variance or spectral shift of the detectedultrasonic waves.
 15. The process according to claim 9, wherein: thespectral comparison is conducted in one of a time period or a frequencyrange in response to spectral variance or spectral shift of the detectedultrasonic waves.
 16. The process according to claim 10, wherein: thespectral comparison is conducted in one of a time period or a frequencyrange in response to spectral variance or spectral shift of the detectedultrasonic waves.
 17. The process according to claim 1, wherein: theultrasonic wave detecting unit is disposed relative to the material sothat only backscattered or back reflected ultrasonic waves are detected.18. The process according to claim 2, wherein: the ultrasonic wavedetecting unit is disposed relative to the material so that onlybackscattered or back reflected ultrasonic waves are detected.
 19. Theprocess according to claim 3, wherein: the ultrasonic wave detectingunit is disposed relative to the material so that only backscattered orback reflected ultrasonic waves are detected.
 20. The process accordingto claim 6, wherein: the ultrasonic-wave-detecting unit is disposedrelative to the material so that only backscattered or back reflectedultrasonic waves are detected.
 21. The process according to claim 6,wherein: the ultrasonic wave detecting unit is disposed relative to thematerial so that only backscattered or back reflected ultrasonic wavesare detected.
 22. The process according to claim 12, wherein: theultrasonic wave detecting unit is disposed relative to the material sothat only backscattered or back reflected ultrasonic waves are detected.23. The process according to claim 1, wherein: the application of heatinside the material occurs by means of selective application to thematerial one of electromagnetic radiation, an alternating electricalfield or an ultrasonic field.
 24. The process according to claim 2,wherein: the application of heat inside the material occurs by means ofselective application to the material one of electromagnetic radiation,an alternating electrical field or an ultrasonic field.
 25. The processaccording to claim 3, wherein: the application of heat inside thematerial occurs by means of selective application to the material one ofelectromagnetic radiation, an alternating electrical field or anultrasonic field.
 26. The process according to claim 4, wherein: theapplication of heat inside the material occurs by means of selectiveapplication to the material one of electromagnetic radiation, analternating electrical field or an ultrasonic field.
 27. The processaccording to claim 6, wherein: the application of heat inside thematerial occurs by means of selective application to the material one ofelectromagnetic radiation, an alternating electrical field or anultrasonic field.
 28. The process according to claim 12, wherein: theapplication of heat inside the material occurs by means of selectiveapplication to the material one of electromagnetic radiation, analternating electrical field or an ultrasonic field.
 29. The processaccording to claim 17, wherein: the application of heat inside thematerial occurs by means of selective application to the material one ofelectromagnetic radiation, an alternating electrical field or anultrasonic field.
 30. A process in accordance with claim 1 wherein: atemperature at the location of structural change is determined byresolving a velocity of the ultrasonic waves at the location of thestructural change.
 31. A device for controlling selective application ofheat into a material, comprising: an ultrasonic wave generating unitwhich couples ultrasonic waves to the material, an ultrasonic wavedetecting unit which detects the ultrasonic waves emerging from thematerial, an evaluation unit which, based upon the detected ultrasonicwaves, generates parameters providing information about thermal andstructural changes inside the material and a heat application unit fordirecting heat to the material; and wherein the ultrasonic wavegenerating unit and the ultrasonic wave detecting unit are positioned topermit coupling of the ultrasonic waves to and detecting of theultrasonic waves from a same location within the material and areadjustable relative to the material and the heat application unit, theheat application unit is disposed in a center of the ultrasonic wavegenerating unit and ultrasonic wave detecting unit, and the ultrasonicwave generating unit and ultrasonic wave detecting unit comprise a twodimensional array.
 32. The device according to claim 31: the ultrasonicwave generating unit and the ultrasonic wave detecting unit arepositioned relative to the material so that the ultrasonic waves actingon the material are focused.
 33. The device according to claim 31,comprising: a housing containing the ultrasonic wave generating unit andthe ultrasonic wave detecting unit which spaces the units apart and thehousing is positionable relative to the material.
 34. The deviceaccording to claim 32, comprising: a housing containing the ultrasonicwave generating unit and the ultrasonic wave detecting unit which spacesthe units apart and the housing is positionable relative to thematerial.
 35. The device according to claim 31, wherein: the ultrasonicwave generating unit and the ultrasonic detecting unit are rotatableabout an axis of rotation which coincides with the axis of the heatapplication unit.
 36. The device according to claim 32 wherein: theultrasonic wave generating unit and the ultrasonic detecting unit arerotatable about an axis of rotation which coincides with the axis of theheat application unit.
 37. The device according to claim 33, wherein:the ultrasonic wave generating unit and the ultrasonic detecting unitare rotatable about an axis of rotation which coincides with the axis ofthe heat application unit.
 38. The device according to claim 34,wherein: the ultrasonic wave generating unit and the ultrasonicdetecting unit are rotatable about an axis of rotation which coincideswith the axis of the heat application unit.
 39. The device according toclaim 31, wherein: the heat application unit is a glass fiber whichguides light into the material.
 40. The device according to claim 32,wherein: the heat application unit is a glass fiber which guides lightinto the material.
 41. The device according to claim 33, wherein: theheat application unit is a glass fiber which guides light into thematerial.
 42. The device according to claim 35, wherein: the heatapplication unit is a glass fiber which guides light into the material.43. The device according to claim 31, wherein: the heat application unitis a diagnostic ultrasonic device which generates a temperature increaseinside a tissue region.
 44. The device according to claim 32, wherein:the heat application unit is a diagnostic ultrasonic device whichgenerates a temperature increase inside a tissue region.
 45. The deviceaccording to claim 33, wherein: the heat application unit is adiagnostic ultrasonic device which generates a temperature increaseinside a tissue region.
 46. The device according to claim 35, wherein:the heat application unit is a diagnostic ultrasonic device whichgenerates a temperature increase inside a tissue region.
 47. The deviceaccording to claim 39, wherein: the heat application unit is adiagnostic ultrasonic device which generates a temperature increaseinside a tissue region.
 48. A device for controlling selectiveapplication of heat into a material, comprising: an ultrasonic wavegenerating unit which couples ultrasonic waves to the material, anultrasonic wave detecting unit which detects the ultrasonic wavesemerging from the material, an evaluation unit which, based upon thedetected ultrasonic waves, generates parameters providing informationabout thermal and structural changes inside the material and a heatapplication unit for directing heat to the material; and wherein theultrasonic wave generating unit and the ultrasonic wave detecting unitare positioned to permit coupling of the ultrasonic waves to anddetecting of the ultrasonic waves from a same location within thematerial and are adjustable relative to the material and the heatapplication unit, the heat application unit is disposed in a center ofthe ultrasonic wave generating unit and ultrasonic wave detecting unit,and the ultrasonic wave generating unit and ultrasonic wave detectingunit comprise a one dimensional array.
 49. The device of claim 48wherein: the ultrasonic wave generating unit and the ultrasonicdetecting unit are rotatable about an axis of rotation which coincideswith the axis of the heat application unit.
 50. The device of claim 48wherein: the heat application unit is a glass fiber which guides lightinto the material.
 51. The device of claim 48 wherein: the heatapplication unit is a diagnostic ultrasonic device which generates atemperature increase inside a tissue region.